The International Organization for legal metrology OIML is an intergovernmental treaty organization, established in 1955 in order to promote the global harmonization of legal metrology procedures.

Since that time, OIML has developed a worldwide technical structure that provides its Members with metrological guidelines for the elaboration of national and regional requirements concerning the manufacture and use of measuring instruments for legal metrology applications. OIML's membership includes Member States, countries that participate actively in technical activities, and Corresponding Members, countries that join OIML as observers.

OIML activities
OIML develops model regulations, International Recommendations, which provide Members with an internationally agreed-upon basis for the establishment of national legislation on various categories of measuring instruments. Given the increasing national implementation of OIML guidelines, more and more manufacturers are referring to OIML International Recommendations to ensure that their products meet international specifications for metrological performance and testing.

Technical committees or subcommittees that are formed by the Member States develop OIML Draft Recommendations and Documents. Certain international and regional institutions also participate on a consultation basis.

Cooperative agreements are established between OIML and certain institutions, such as ISO and IEC, with the objective of avoiding contradictory requirements; consequently, manufacturers and users of measuring instruments, test laboratories, etc. may apply simultaneously OIML Publications and those of other institutions.

OIML organization
Every 4 years the International Conference for Legal Metrology (the Conference) meets. At this occasion OIML Member State delegations and observers from Corresponding Members and liaison international and regional institutions assemble to define general policy and budgetary lines for the Organization, and to promote national implementation of OIML metrological guidelines.

The International Committee for Legal metrology (CIML) is the steering committee for OIML. The CIML meets annually to review the Organization's technical progress and administrative operations. The Committee is composed of appointed representatives of OIML Member States.

International consensus in the legal metrology community is reached through OIML Technical Committees and Sub-committees, of which 18 exist nowadays. The composition includes representatives from Member States, international standardization and technical organizations, manufacturers' associations and regional regulatory bodies. Under the coordination of a secretariat, experts establish international technical guidelines for the metrological performance and testing procedures of measuring instruments subject to legal controls.

The Bureau International de Métrologie Légale (BIML) is the secretariat and headquarters of the OIML. It ensures both the day to day running of activities and the planning of longer-term actions. The BIML coordinates and informs CIML Members of technical work undertaken by OIML Technical Committees (of which there are currently eighteen), organizes OIML Conference and Committee Meetings and manages the finances of the Organization.